Replace pqueue with code from hashsig heap

I accidentally wrote a separate priority queue implementation when
I was working on file rename detection as part of the file hash
signature calculation code.  To simplify licensing terms, I just
adapted that to a general purpose priority queue and replace the
old priority queue implementation that was borrowed from elsewhere.

This also removes parts of the COPYING document that no longer
apply to libgit2.

Author: arrbee

COPYING

@@ -388,19 +388,7 @@ Copyright (C) 1995-2010 Jean-loup Gailly and Mark Adler
 
 ----------------------------------------------------------------------
 
-The priority queue implementation is based on code licensed under the
-Apache 2.0 license:
-
-	Copyright 2010 Volkan Yazıcı <[email protected]>
-	Copyright 2006-2010 The Apache Software Foundation
-
-The full text of the Apache 2.0 license is available at:
-
-	http://www.apache.org/licenses/LICENSE-2.0
-
-----------------------------------------------------------------------
-
-The Clay framework is licensed under the MIT license:
+The Clar framework is licensed under the MIT license:
 
 Copyright (C) 2011 by Vicent Marti
 
@@ -930,64 +918,3 @@ necessary.  Here is a sample; alter the names:
 That's all there is to it!
 
 ----------------------------------------------------------------------
-
-Portions of src/win32/posix_w32.c are derrived from link_win32.c in PHP:
-
--------------------------------------------------------------------- 
-                  The PHP License, version 3.01
-Copyright (c) 1999 - 2012 The PHP Group. All rights reserved.
--------------------------------------------------------------------- 
-
-Redistribution and use in source and binary forms, with or without
-modification, is permitted provided that the following conditions
-are met:
-
-  1. Redistributions of source code must retain the above copyright
-     notice, this list of conditions and the following disclaimer.
- 
-  2. Redistributions in binary form must reproduce the above copyright
-     notice, this list of conditions and the following disclaimer in
-     the documentation and/or other materials provided with the
-     distribution.
- 
-  3. The name "PHP" must not be used to endorse or promote products
-     derived from this software without prior written permission. For
-     written permission, please contact [email protected].
-  
-  4. Products derived from this software may not be called "PHP", nor
-     may "PHP" appear in their name, without prior written permission
-     from [email protected].  You may indicate that your software works in
-     conjunction with PHP by saying "Foo for PHP" instead of calling
-     it "PHP Foo" or "phpfoo"
- 
-  5. The PHP Group may publish revised and/or new versions of the
-     license from time to time. Each version will be given a
-     distinguishing version number.
-     Once covered code has been published under a particular version
-     of the license, you may always continue to use it under the terms
-     of that version. You may also choose to use such covered code
-     under the terms of any subsequent version of the license
-     published by the PHP Group. No one other than the PHP Group has
-     the right to modify the terms applicable to covered code created
-     under this License.
-
-  6. Redistributions of any form whatsoever must retain the following
-     acknowledgment:
-     "This product includes PHP software, freely available from
-     <http://www.php.net/software/>".
-
-THIS SOFTWARE IS PROVIDED BY THE PHP DEVELOPMENT TEAM ``AS IS'' AND 
-ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
-THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 
-PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE PHP
-DEVELOPMENT TEAM OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
-INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
-(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
-SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
-HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
-STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
-OF THE POSSIBILITY OF SUCH DAMAGE.
-
--------------------------------------------------------------------- 
-

src/commit_list.c

@@ -11,10 +11,10 @@
 #include "pool.h"
 #include "odb.h"
 
-int git_commit_list_time_cmp(void *a, void *b)
+int git_commit_list_time_cmp(const void *a, const void *b)
 {
-	git_commit_list_node *commit_a = (git_commit_list_node *)a;
-	git_commit_list_node *commit_b = (git_commit_list_node *)b;
+	const git_commit_list_node *commit_a = a;
+	const git_commit_list_node *commit_b = b;
 
 	return (commit_a->time < commit_b->time);
 }

src/commit_list.h

@@ -39,7 +39,7 @@ typedef struct git_commit_list {
 } git_commit_list;
 
 git_commit_list_node *git_commit_list_alloc_node(git_revwalk *walk);
-int git_commit_list_time_cmp(void *a, void *b);
+int git_commit_list_time_cmp(const void *a, const void *b);
 void git_commit_list_free(git_commit_list **list_p);
 git_commit_list *git_commit_list_insert(git_commit_list_node *item, git_commit_list **list_p);
 git_commit_list *git_commit_list_insert_by_date(git_commit_list_node *item, git_commit_list **list_p);

src/graph.c

@@ -1,4 +1,3 @@
-
 /*
  * Copyright (C) the libgit2 contributors. All rights reserved.
  *
@@ -13,9 +12,9 @@
 static int interesting(git_pqueue *list, git_commit_list *roots)
 {
 	unsigned int i;
-	/* element 0 isn't used - we need to start at 1 */
-	for (i = 1; i < list->size; i++) {
-		git_commit_list_node *commit = list->d[i];
+
+	for (i = 0; i < git_pqueue_size(list); i++) {
+		git_commit_list_node *commit = git_pqueue_get(list, i);
 		if ((commit->flags & STALE) == 0)
 			return 1;
 	}
@@ -42,7 +41,7 @@ static int mark_parents(git_revwalk *walk, git_commit_list_node *one,
 		return 0;
 	}
 
-	if (git_pqueue_init(&list, 2, git_commit_list_time_cmp) < 0)
+	if (git_pqueue_init(&list, 0, 2, git_commit_list_time_cmp) < 0)
 		return -1;
 
 	if (git_commit_list_parse(walk, one) < 0)
@@ -59,10 +58,9 @@ static int mark_parents(git_revwalk *walk, git_commit_list_node *one,
 
 	/* as long as there are non-STALE commits */
 	while (interesting(&list, roots)) {
-		git_commit_list_node *commit;
+		git_commit_list_node *commit = git_pqueue_pop(&list);
 		int flags;
 
-		commit = git_pqueue_pop(&list);
 		if (commit == NULL)
 			break;
 
@@ -110,16 +108,16 @@ static int ahead_behind(git_commit_list_node *one, git_commit_list_node *two,
 {
 	git_commit_list_node *commit;
 	git_pqueue pq;
-	int i;
+	int error = 0, i;
 	*ahead = 0;
 	*behind = 0;
 
-	if (git_pqueue_init(&pq, 2, git_commit_list_time_cmp) < 0)
+	if (git_pqueue_init(&pq, 0, 2, git_commit_list_time_cmp) < 0)
 		return -1;
-	if (git_pqueue_insert(&pq, one) < 0)
-		goto on_error;
-	if (git_pqueue_insert(&pq, two) < 0)
-		goto on_error;
+
+	if ((error = git_pqueue_insert(&pq, one)) < 0 ||
+		(error = git_pqueue_insert(&pq, two)) < 0)
+		goto done;
 
 	while ((commit = git_pqueue_pop(&pq)) != NULL) {
 		if (commit->flags & RESULT ||
@@ -132,18 +130,15 @@ static int ahead_behind(git_commit_list_node *one, git_commit_list_node *two,
 
 		for (i = 0; i < commit->out_degree; i++) {
 			git_commit_list_node *p = commit->parents[i];
-			if (git_pqueue_insert(&pq, p) < 0)
-				return -1;
+			if ((error = git_pqueue_insert(&pq, p)) < 0)
+				goto done;
 		}
 		commit->flags |= RESULT;
 	}
 
+done:
 	git_pqueue_free(&pq);
-	return 0;
-
-on_error:
-	git_pqueue_free(&pq);
-	return -1;
+	return error;
 }
 
 int git_graph_ahead_behind(size_t *ahead, size_t *behind, git_repository *repo,

src/merge.c

@@ -161,10 +161,10 @@ int git_merge_base(git_oid *out, git_repository *repo, const git_oid *one, const
 
 static int interesting(git_pqueue *list)
 {
-	unsigned int i;
-	/* element 0 isn't used - we need to start at 1 */
-	for (i = 1; i < list->size; i++) {
-		git_commit_list_node *commit = list->d[i];
+	size_t i;
+
+	for (i = 0; i < git_pqueue_size(list); i++) {
+		git_commit_list_node *commit = git_pqueue_get(list, i);
 		if ((commit->flags & STALE) == 0)
 			return 1;
 	}
@@ -186,7 +186,7 @@ int git_merge__bases_many(git_commit_list **out, git_revwalk *walk, git_commit_l
 			return git_commit_list_insert(one, out) ? 0 : -1;
 	}
 
-	if (git_pqueue_init(&list, twos->length * 2, git_commit_list_time_cmp) < 0)
+	if (git_pqueue_init(&list, 0, twos->length * 2, git_commit_list_time_cmp) < 0)
 		return -1;
 
 	if (git_commit_list_parse(walk, one) < 0)
@@ -205,10 +205,11 @@ int git_merge__bases_many(git_commit_list **out, git_revwalk *walk, git_commit_l
 
 	/* as long as there are non-STALE commits */
 	while (interesting(&list)) {
-		git_commit_list_node *commit;
+		git_commit_list_node *commit = git_pqueue_pop(&list);
 		int flags;
 
-		commit = git_pqueue_pop(&list);
+		if (commit == NULL)
+			break;
 
 		flags = commit->flags & (PARENT1 | PARENT2 | STALE);
 		if (flags == (PARENT1 | PARENT2)) {